// Copyright (c) 2014. Evgeny Nazarov
// http://guardly.codeplex.com/
// All rights reserved.
// 
// Redistribution and use in source and binary forms, 
// with or without modification, are permitted provided 
// that the following conditions are met:
// 
//     * Redistributions of source code must retain the 
//     above copyright notice, this list of conditions and 
//     the following disclaimer.
//     
//     * Redistributions in binary form must reproduce 
//     the above copyright notice, this list of conditions 
//     and the following disclaimer in the documentation 
//     and/or other materials provided with the distribution.
//     
//     * Neither the name of contributors may be used to endorse 
//     or promote products derived from this software 
//     without specific prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 
// CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, 
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
// SUCH DAMAGE.
// 
// [This is the BSD license, see http://www.opensource.org/licenses/bsd-license.php]

namespace Guardly
{
    using System;

    /// <summary>
    /// Base class for guarded value wrappers.
    /// </summary>
#if !DEBUG
    [System.Diagnostics.DebuggerNonUserCode]
#endif
    public abstract class GuardBase : IEquatable<GuardBase>
    {
        private readonly int hashCode;

        internal GuardBase(int hashCode)
        {
            this.hashCode = hashCode;
        }

        /// <summary>
        /// Indicates whether the current object is equal to another object of the same type.
        /// </summary>
        /// <param name="other">An object to compare with this object.</param>
        /// <returns>true if the current object is equal to the <paramref name="other"/> parameter; otherwise, false.</returns>
        public bool Equals(GuardBase other)
        {
            if (ReferenceEquals(other, null))
            {
                return false;
            }

            if (ReferenceEquals(other, this))
            {
                return true;
            }

            if (GetType() != other.GetType())
            {
                return false;
            }

            return GetHashCode() == other.GetHashCode();
        }

        /// <summary>
        /// Determines whether the specified <see cref="T:System.Object"/> is equal to the current <see cref="T:System.Object"/>.
        /// </summary>
        /// <param name="obj">The <see cref="T:System.Object"/> to compare with the current <see cref="T:System.Object"/>. </param>
        /// <returns>true if the specified <see cref="T:System.Object"/> is equal to the current <see cref="T:System.Object"/>; otherwise, false.</returns>
        public sealed override bool Equals(object obj)
        {
            return obj is GuardBase && Equals(obj as GuardBase);
        }

        /// <summary>
        /// Serves as a hash function for a particular type. 
        /// </summary>
        /// <returns>A hash code for the current <see cref="T:System.Object"/>.</returns>
        public sealed override int GetHashCode()
        {
            return hashCode;
        }
    }
}